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High-speed imaging was used to record the prey-tracking behavior of larval zebrafish as they fed upon paramecium. Prey tracking is comprised of a variable set of discrete locomotor movements that together align the larva with the paramecium and bring it into close proximity, usually within one body length. These tracking behaviors are followed by a brief capture swim bout that was previously described [Borla et al., 2002]. Tracking movements were classified as either swimming or turning bouts. The swimming bouts were similar to a previously characterized larval slow swim [Budick and O’Malley, 2000], but the turning movements consisted of unique J-shaped bends which appear to minimize forward hydrodynamic disturbance when approaching the paramecium. Such J-turn tracking bouts consisted of multiple unilateral contractions to one side of the body. J-turns slowly and moderately alter the orientation of the larva – this is in contrast to previously described escape and routine turns. Tracking behaviors appear to be entirely visually guided. Infra-red (IR) imaging of locomotor behaviors in a dark environment revealed a complete absence of tracking behaviors, even though the normal repertoire of other locomotive behaviors was recorded. Concomitantly, such larvae were greatly impaired in consuming paramecia. The tracking behavior is of interest because it indicates the presence of sophisticated locomotor control circuitry in this relatively simple model organism. Such locomotor strategies may be conserved and elaborated upon by other larval and adult fishes. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Swimming and turning behaviors of larval zebrafish have been described kinematically, but prey capture behaviors are less well characterized. High-speed digital imaging was used to record the axial kinematics of larval zebrafish as they preyed upon paramecia and also during other types of swimming. In all types of swim bouts, a series of traveling waves of bending is observed and these bends propagate along the trunk in the rostral to caudal direction. The prey capture swim bouts appeared to be more complex than other swim patterns examined. In the capture swim bouts, the initial bends were of low amplitude and were most prominent at far-caudal locations during each individual traveling wave of bending. Later bends in the bout (occurring just prior to prey capture) appeared to originate more rostrally and were of larger amplitude. These changes in bending pattern during capture swims were accompanied by a marked increase in tail-beat frequency. Associated with these axial kinematics were changes in heading and an abrupt increase in velocity close to the moment of prey capture. These changing patterns of bending suggest precise, bend-to-bend, neural control over both the timing and the rostral-caudal locus of bending. This degree of ‘fine axial motor control’ has not previously been described in the teleost behavioral literature and is notable because it occurs in larval zebrafish, where descending control signals are funneled through the roughly three-hundred neurons that project from brain into spinal cord. These findings will necessitate a significant increase in the complexity of current models of descending motor control in fishes.Copyright © 2002 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]